Roofing membrane with release liner having enhanced friction characteristics

ABSTRACT

A roofing membrane includes a waterproofing layer, and a release liner removably attached to the waterproofing membrane. The release liner has a coefficient of friction greater than the coefficient of friction of the material of the waterproofing membrane. The release liner is preferably left in place after initial installation of the roofing membrane on a roof, and removed near the end of construction, so that the waterproofing membrane is at least partially protected from damage and dirt during later parts of the construction.

BACKGROUND

Low slope or flat roofs are typically covered with waterproofingmaterials. In a “built up roof” (BUR), multiple components such asliquid asphalt and ballast are separately applied to the roof, oftenover an insulation layer. An alternative to the built up roof is to usea “singly-ply” membrane. A single ply membrane may be a large, flat,flexible membrane supplied on a roll, and rolled out on top of the roof,typically on top of the insulation layer. The term “single-ply” is usedto describe a roof having a single application of a membrane, but themembrane itself may comprise multiple layers such as polymer layers,reinforcing layers, adhesive layers, coatings, and the like. Typicalbase materials used for single ply membranes are thermoplasticpolyolefin (TPO), ethylene propylene diene monomer (EPDM), polyvinylchloride (PVC), and modified bitumen.

A single ply membrane may be supplied in any workable size, for examplein rolls up to 50 feet wide or more containing 100 linear feet or moreof membrane. When a roof is too large to be covered by a single piece ofmembrane, multiple pieces may be overlapped and joined at the seamsusing a waterproof joining method such as heat welding or adhesivebonding. More detail about the use of single ply membranes may be foundin U.S. Patent Application Publication No. 2016/0362894, published Dec.15, 2016 and titled “Sheet Roofing with Pre-Taped Seams and TapeTherefor”, the entire disclosure of which is hereby incorporated byreference herein for all purposes.

FIG. 1 illustrates a typical flat roof installation. Building 100 has aflat roof 101, covered by rows of a single ply membrane 102. The rows ofsingle ply membrane 102 have been joined at their adjacent seams 103, sothat roof 101 has been covered with a continuous waterproof barrier,other than at necessary penetrations of the roof. For example, as istypical, a number of pieces of electrical and mechanical equipment maybe placed on roof 101, and may require connections to through the roofto other equipment inside building 100. In FIG. 1, air conditioningequipment 104, a cellular telephone site 105, and a plumbing drain vent106 are illustrated, but on other roofs, other kinds of equipment may bepresent. On a large roof, dozens of pieces of equipment may be present,or more.

Roofing membrane 102 may preferably be white in color, to reflectsunlight and reduce the energy required to cool building 100. Whileroofing membrane 102 may be installed in a clean and undamagedcondition, access to equipment on the roof may require that workers walkon roofing membrane 102, for example to seal roofing membrane 102 aroundthe penetrations, or to install and connect the equipment at a laterstage in the construction of building 100.

It is desirable that workers be provided access to the roof as needed,safely, and without damaging or discoloring roofing membrane 102.

BRIEF SUMMARY

According to one aspect, a roofing membrane comprises a waterproofinglayer having a top major surface bounded by four edges and a releaseliner removably attached to and covering or substantially covering thetop major surface of the waterproofing layer. The release liner has acoefficient of friction higher than the coefficient of friction of thematerial of the waterproofing layer.

According to another aspect, a method of applying a roofing membrane ona roof comprises laying a first row of roofing membrane on the roof, thefirst row of roofing membrane including a first waterproofing layer anda first release liner on top of a top major surface of the firstwaterproofing layer. The first release liner has a coefficient offriction higher than that of the material of the first waterproofinglayer. The method further comprises laying a second row of roofingmembrane on the roof, the second row of roofing membrane having a secondwaterproofing layer and a second release liner. The second release linerhas a coefficient of friction higher than that of the material of thesecond waterproofing layer. The second row of roofing membrane overlapsthe first row such that a bottom major surface of the secondwaterproofing layer contacts an uncovered strip at one edge of the topmajor surface of the first waterproofing layer. The method furthercomprises bonding the first and second rows of roofing membrane togetherin their area of overlap.

According to another aspect, a method of making a roofing membranecomprises providing a polymeric waterproofing layer having a top majorsurface, and removably attaching a release liner to the top majorsurface of the waterproofing layer.

The release liner has a coefficient of friction higher than that of thematerial of the waterproofing layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a typical flat roof installation on a building.

FIG. 2 shows a cross-section view of a roofing membrane in accordancewith embodiments of the invention.

FIG. 3 shows a perspective view of the roofing membrane of FIG. 2, witha release liner partially pulled back from a waterproofing layer, inaccordance with embodiments of the invention.

FIG. 4 shows a release liner according to other embodiments of theinvention.

FIG. 5 illustrates a roofing membrane in accordance with otherembodiments of the invention.

FIG. 6 illustrates a method of installing a roofing membrane, inaccordance with embodiments of the invention.

FIG. 7 illustrates a roofing membrane in accordance with otherembodiments or the invention.

FIG. 8 illustrates a method of installing a roofing membrane, inaccordance with other embodiments of the invention.

FIG. 9 illustrates a roofing membrane having a release liner that has anembossed surface, in accordance with embodiments of the invention.

FIG. 10 illustrates one example technique for producing a roofingmembrane in accordance with embodiments of the invention.

FIG. 11 illustrates an embossing pattern in accordance with embodimentsof the invention.

FIG. 12 illustrates an embossing pattern in accordance with otherembodiments of the invention.

FIG. 13 illustrates an embossing pattern in accordance with otherembodiments of the invention.

FIG. 14 illustrates an embossing pattern in accordance with otherembodiments of the invention.

FIG. 15 illustrates an embossing pattern in accordance with otherembodiments of the invention.

FIG. 16 illustrates an embossing pattern in accordance with otherembodiments of the invention.

FIG. 17 illustrates an embossing pattern in accordance with otherembodiments of the invention.

DETAILED DESCRIPTION

FIG. 2 shows a cross-section view of a roofing membrane 201 inaccordance with embodiments of the invention. Roofing membrane 201 is asingle ply membrane having two layers—a waterproofing layer 202 and arelease liner 203.

Waterproofing layer 202 may be made of any suitable material, and indifferent embodiments may comprise thermoplastic polyolefin (TPO),ethylene propylene diene monomer (EPDM), polyvinyl chloride (PVC),modified bitumen, or a combination of materials. Waterproofing layer 202may have any suitable thickness, for example between 0.020 and 0.250inches, preferably between 0.040 and 0.125 inches. Roofing membrane 201may be supplied in rolls of any workable size, for example rolls up to50 feet wide or more containing 100 linear feet or more of membrane,such that membrane 201 is supplied in rectangular sheets up to 50×100feet or more. The top face of the membrane may be termed the top majorsurface, and is bounded by four edges forming the rectangular perimeterof the sheet. Similarly, waterproofing layer 202 has a bottom majorsurface opposite the top major surface and intended to be placed againsta roof.

While waterproofing layer 202 is shown monolithically, it may includeother materials and layers. For example, waterproofing layer 202 mayinclude an embedded reinforcing mesh made of fiberglass or othermaterials. In another example, waterproofing layer 202 may include anadhesive on its bottom major surface such that roofing membrane 201 isself-adhesive. In this case, another release liner (not shown) may beprovided below the adhesive layer.

Smaller rolls may be provided if desired. In addition, compatiblepatching sheets, cap sheets, tapes, and other items may be madeavailable for convenient installation of membrane 201 on roofs ofvarious shapes and sizes.

The top major surface of waterproofing layer 202 is preferably light incolor, for example white.

Release liner 203 is preferably a thin layer removably attached to thetop major surface of waterproofing layer 202, and covering orsubstantially covering the top major surface. Release liner 203 isintended to be removed as a last or nearly-last step in the installationof roofing membrane 201 on a roof. Roofing membrane 201 may be installedwith release liner 203 in place, and workers permitted to walk on theroof (on top of release liner 203) to complete later tasks in theconstruction or re-roofing of the building. For example, workers mayseal joints between strips of roofing membrane 201, may seal around anypenetrations of the roof, may install and connect electrical ormechanical equipment on the roof, or may perform other tasks.

Once such tasks are completed, it may be expected that foot traffic onthe roof will be negligible. Near the end of the project, release liner203 is removed, exposing the top major surface of waterproofing layer202, in pristine or near-pristine condition. Release liner 203substantially protects waterproofing layer 202 from dirt, scuffs, wear,or other events that might otherwise be detrimental to the integrity andreflectivity of waterproofing layer 202, and obviates the need forexpensive and time-consuming cleaning of the newly-installed roof. Afterremoval, release liner 203 may be discarded or preferably recycled.

Release liner 203 may conveniently be made of one or more layers of oneor more polyolefins such as polypropylene or polyethylene, but in otherembodiments may be made of any suitable material or combination ofmaterials. Release liner 203 may be made of recycled materials, and maybe recyclable once removed.

In particular, release liner 203 has a coefficient of friction greaterthan that of the material of waterproofing layer 202 itself. Forexample, a TPO membrane may have a kinetic coefficient of friction ofabout 0.575, and release liner 203 may have a kinetic coefficient offriction greater than 0.575, and thus may be considered to have enhancedfriction characteristics, as compared with the material of waterproofinglayer 202. In other embodiments, release liner 203 may have a kineticcoefficient of friction of at least 0.6, at least 0.7, at least 0.8, atleast 0.9, at least 0.95, or another value. In one embodiment, releaseliner 203 has a kinetic coefficient of friction of about 0.965.

For the purposes of this disclosure, recited coefficients of frictionare kinetic coefficients unless otherwise stated. The kineticcoefficient of friction is also sometimes known as the dynamiccoefficient of friction, and is a unitless ratio computed by dividingthe force required to drag one object over another by the normal forcebetween the objects, once motion has begun. As is well known, thekinetic coefficient of friction of a material is generally lower thanthe static coefficient of friction. The static coefficient of frictionis the unitless ratio computed by dividing the force required to startdragging motion between two objects by the normal force between them.

Also for the purposes of this disclosure, kinetic coefficients offriction were measured using a modified version of the ASTM1894—“Standard Test Method for Static and Kinetic Coefficients ofFriction of Plastic Film and Sheeting” method. In the standard ASTM 1894test, a weighted sled is pulled across a second stationary, flat surfaceat a speed of 150 mm/min, and the contacting surfaces of the weightedsled and the flat surface are made of the same material under test. Inthe modified procedure used in this disclosure, the sled is covered inrubber and the flat surface is the release liner being tested. This isin order to find the coefficient of friction between the rubber (such asa sole of a shoe) and the liner. The test fixture used to measure thecoefficient of friction was a Custom Scientific Instruments, Inc.CS-1525-007.

Release liner 203 may be removably attached to waterproofing layer 202in any suitable way. In some embodiments, release liner 203 may beattached to waterproofing layer 202 using an adhesive such as a hot-meltadhesive, a pressure sensitive adhesive, a urethane based adhesive, anpolyisoprene based adhesive, or another kind of adhesive. In someembodiments, any adhesive may be applied across the entire releaseliner. In other embodiments, the adhesive may be applied in bands,patches, or another pattern in which less than the entire surface of therelease liner is covered, in order to reduce the amount of adhesiverequired or to reduce the force needed to separate the release linerfrom the waterproofing layer.

For example, FIG. 3 shows a perspective view of roofing membrane 201with release liner 203 partially pulled back from waterproofing layer202, in accordance with embodiments of the invention. The underside 301of release liner 203 is uniformly coated with adhesive. FIG. 4 showsanother embodiment, in which underside 301 of release liner 203 iscoated with patches 401 of adhesive, such that less than the entireunderside 301 is coated. Any other suitable partial coating techniquemay be used, including random splattering of the adhesive.

Any adhesive used may be environmentally friendly. For example, theadhesive may be biodegradable, or water soluble, or may have otherproperties for low environmental impact.

In other embodiments, water proofing layer 202 and release liner 203 maybe removably attached without the use of any adhesive. For example,either or both of release liner 203 and waterproofing layer 202 may bestatically charged, so that they are attached by electrostaticattraction. In some embodiments, waterproofing layer 202 and releaseliner 203 may simply subjected to heat and pressure during themanufacturing of roofing membrane 201, forming a temporary lightattachment between the two.

In some embodiments, release liner 203 may include a tackifier in itsformulation, so that it tends to cling to waterproofing layer 202without being fully adhered. Various additives for imparting tack to theformulation of release liner 203 are available. For example, theVistamaxx® line of polymers available from ExxonMobil includes polymerswith good tack properties.

FIG. 5 illustrates a roofing membrane 501 in accordance with otherembodiments. In this example embodiment, release liner 203 is split, sothat it may be removed from waterproofing layer 202 in two pieces. Thismay allow for more convenient handling of release liner 203 duringremoval. Preferably, the edges of the two pieces of release liner 203meet at a zero-width or near-zero-width slit 502, so that the uppermajor surface of waterproofing layer 202 remains protected.

FIG. 6 illustrates a method of installing a roofing membrane, inaccordance with embodiments of the invention. A roofing membrane such asroofing membrane 201 is shown in this example. Roofing membrane 201 ahas been previously laid on a roof, and its release liner 203 lifted andfolded back to form a flap 601 along one edge 602 of roofing membrane201 a. A second piece of roofing membrane, 201 b, is unrolled and placedsuch that the bottom major surface of roofing membrane 201 b overlapsand lies on top of the exposed portion of the top major surface ofroofing membrane 201 a, as shown at 603. The two roofing membranes maybe joined and sealed by any suitable technique, for example by heatwelding, by an adhesive pre-applied to either or both of roofingmembranes 201 a and 201 b, or by an adhesive applied on the rooftopduring installation. The overlapping area of the two roofing membranesis preferably wide enough to ensure a good seal between the membranes201 a and 201 b. In some embodiments, the overlapping area may be about2 to 6 inches wide, for example about 4 inches wide.

The flap 601 of release liner 203 folded back from roofing membrane 201a may conveniently be laid back down on top of the overlapping portionof roofing membrane 201 b. In other embodiments, the flap may be cutoff, or left loose. In some embodiments, release liner 203 may beperforated to allow for easy removal of flap 601.

FIG. 7 illustrates a roofing membrane 701 in accordance with otherembodiments or the invention. Roofing membrane 701 is similar to roofingmembrane 201 in that it includes a waterproofing layer 702 and a releaseliner 703. However, while release liner 703 substantially covers the topmajor surface of waterproofing layer 702, it does not completely coverthe top major surface of waterproofing layer 702. Rather, a strip 704 ofthe top major surface of waterproofing layer 702 is left uncovered byrelease liner 703, along one edge 705 of waterproofing layer 702.

This arrangement facilitates installation of roofing membrane 701, asshown in FIG. 8. A second row of roofing membrane 701 b can beoverlapped and sealed to a previously-laid first row 701 a without theneed to remove or fold back any release liner from strip 704 along edge705 of the first row 701 a of release liner. The overlapped area shownat 803 can be sealed in any suitable manner, as discussed above.

The coefficient of friction of release liner 203 may be enhanced, forexample using a chemical additive in the material of release liner 203.In some embodiments, release liner 203 may comprise a styrene blockcopolymer such as Kraton® styrene block copolymer available from KratonCorporation of Houston, Tex., USA, or a Vistamaxx® polymer availablefrom ExxonMobil Chemical Company of Spring, Tex., USA.

Methods of producing a plastic film having an enhanced coefficient offriction are given in U.S. Patent Application Publication No.2018/0117874 of Rothbauer et al., published May 3, 2018 and titled“Reusable, Non-Adhesive Protective Cover”, the entire disclosure ofwhich is hereby incorporated by reference herein for all purposes.

As is discussed above, the coefficient of friction of a release linerembodying the invention may be enhanced by the use of an additive in thematerial of the release liner. In addition or alternatively, the releaseliner may be textured or otherwise formed, for example with raisedbumps, to provide a mechanical enhancement to its frictioncharacteristics. In one example, FIG. 9 illustrates a roofing membrane901 having a release liner 902 that has an embossed surface, inaccordance with embodiments of the invention. In this example, releaseliner 902 has a number of elongated bumps 903 arranged at crossingangles, creating a pattern similar to that often used on steel stairtreads for enhancing traction. In other embodiments, bumps 903 may be ofany suitable shape, for example round, polygonal, irregular, or anothershape, and may be placed in any suitable arrangement, for example in apattern or randomly.

In other embodiments, the pattern on the protective film may be formedby one or more of horizontal lines, vertical lines, diagonal lines,squares, or diamond patterns. Also usable are patterns generated fromembossing shapes such as random rough texture, squares, invertedsquares, dotlines and reversed dotlines. In other embodiments, recessesmay be formed into release liner 902, rather than raised bumps.

The sizes of the raised features may range from 0.1 mm to 25 mm, and thefeatures may be arranged in a repeating pattern that repeats every 0.1to 25 mm or more across the release liner. He height of any raisedfeatures (or depth of any recessed features) may preferably be between0.001 mm to 0.1 mm, although other heights may be used. The heights ofbumps 903 may be exaggerated in FIG. 9.

In one preferred embodiment, the embossed pattern is made up ofrepeating adjacent diamond-shapes about 1.2 mm across and a height ofabout 0.20 mm.

Methods of producing a plastic film having an embossed surface are givenin U.S. Patent Application Publication No, 2018/0117874 of Rothbauer etal., previously incorporated by reference.

FIG. 10 illustrates one example technique for producing a roofingmembrane in accordance with embodiments of the invention. In thisexample, both the waterproofing layer 202 and the release liner 203 havebeen previously fabricated and stored on rolls. A first roll 1001 ofwaterproofing layer 202 and a second roll 1002 of release liner 203 aremounted on shafts. Release liner 203 may optionally be fed between anembossing roller 1003 (the roughness of which is exaggerated in FIG. 10)and a rubber roller 1004, to raise bumps on release liner 203,transforming release liner 203 into an embossed release liner such asrelease liner 902 discussed above. Waterproofing layer 202 is also fedoff of roll 1001, and waterproofing layer 202 and release liner 902 arebrought together at compression rollers 1005, where release liner 902 isremovably attached to waterproofing layer 202. Optionally, an adhesivemay be placed between waterproofing layer 202 and release liner 902, forexample by an extruder or other dispenser 1006. The completed roofingmembrane is then wound onto a roll 1007 for packaging and shipment.

Within this basic framework, many variations are possible. For example,embossing roller 1003 may be omitted, so that the resulting roofingmembrane is similar to un-embossed roofing membrane 201. In otherembodiments, either or both of waterproofing layer 202 and release liner203 may be fabricated, for example by extrusion, immediately beforebeing brought together to form a complete roofing membrane. In otherembodiments, waterproofing layer 202 and release liner 203 may becoextruded onto a single roller. Any workable combination of steps andprocesses may be used.

EXAMPLES

A number of example release liners were produced and characterized, assummarized in Table 1 below. Also included in Table 1 is a comparativereading taken from a TPO membrane having no release liner. In all of theexamples of Table 1, no chemical additives or treatments were includedin the release liner for the specific purpose of enhancing the frictioncharacteristics of the release liner. The heights of the embossedfeatures were between 20 and 250 micrometer (0.02 and 0.25 mm).

TABLE 1 Friction Effect of Example Release Liners Liner Emboss StaticKinetic % Δ % Δ Liner Material Pattern COF COF Static COF Kinetic COFComparative TPO N/A N/A 0.688 0.575 N/A N/A Membrane - no liner 1 NylonTaffeta 0.755 0.803 9.74% 39.69% 2 Polypropylene Diamond 0.984 0.96542.95% 67.97% 3 Rubber Matte/Smooth 0.667 0.604 −3.12% 5.13% 4Polypropylene Linen 0.524 0.470 −23.91% −18.28% 5 Polypropylene OrangePeel 0.482 0.390 −30.01% −32.11% 6 Polypropylene Suede 0.622 0.593−9.67% 3.13% 7 Polyprpylene Stipple 0.699 0.665 1.60% 15.67% 8Polypropylene Matte 0.800 0.802 16.28% 39.60% 9 Polypropylene Taffeta0.692 0.587 0.58% 2.18% 10 Polypropylene Matte 0.793 0.784 15.26% 36.47%

The various embossing patterns are illustrated in FIGS. 11-17.

FIG. 11 illustrates an embossing pattern having intersecting embossedlines forming rectangles. In the example of FIG. 11, the rectangles aresquares about 0.5 mm on a side, and are oriented at a 45-degree angle tothe edges of the release liner. In other embodiments, the rectangles maybe at any other orientation angle, including aligned with the edges ofthe release liner. Rectangles of other sizes may be used. The pattern ofFIG. 11 is denoted as a “taffeta” pattern, but this name is forconvenient reference only, and is not to be taken as limiting in anyway.

FIG. 12 illustrates an embossing pattern having intersecting embossedlines forming diamond shapes. In the example of FIG. 12, the diamondshapes are about 2.0 by 4.0 mm, with their long axis aligned with anedge of the release liner. In other embodiments, the diamond shapes maybe at any other orientation angle, and may be of other sizes. Thepattern of FIG. 12 is denoted as a “diamond” pattern, but this name isfor convenient reference only, and is not to be taken as limiting.

FIG. 13 illustrates an embossing having small, randomly orientedembossed bumps. In the example of FIG. 13, the bumps are between about0.1 and 0.3 mm in size. The pattern of FIG. 13 is denoted as a “matte”pattern, but this name is for convenient reference only, and is not tobe taken as limiting.

FIG. 14 illustrates an embossing pattern having intersecting embossedlines forming rectangular shapes. Some of the lines are wider thanothers, and form a pattern of larger rectangles having dimensions ofabout 0.5 to 3.0 mm on each side. Within the larger rectangles, narrowerlines form approximately square features about 0.3 mm on a side. Therectangular features are aligned with an edge of the release liner inFIG. 14, but other sizes or orientations may be used. The pattern ofFIG. 14 is denoted as a “linen” pattern, but this name is for convenientreference only, and is not to be taken as limiting.

FIG. 15 illustrates another embossing pattern having small, randomlyoriented embossed bumps. The example of FIG. 15 may be similar to theexample of FIG. 13, except that the bumps are somewhat larger. Thepattern of FIG. 15 is denoted as a “matte” pattern, but this name is forconvenient reference only, and is not to be taken as limiting.

FIG. 16 illustrates another embossing pattern having small, randomlyoriented embossed bumps. The example of FIG. 16 may be similar to theexamples of FIGS. 13 and 15, except that the bumps are still larger, andare elongated so that they intertwine with each other to a degree. Thepattern of FIG. 16 is denoted as a “suede” pattern, but this name is forconvenient reference only, and is not to be taken as limiting.

FIG. 17 illustrates another embossing pattern having randomly orientedembossed bumps. The example of FIG. 17 may be similar to other examples,except that the bumps are still larger. In FIG. 17, the bumps arebetween about 0.5 and 1.0 mm across, but other sizes may be used. Thepattern of FIG. 17 is denoted as a “stipple” pattern, but this name isfor convenient reference only, and is not to be taken as limiting.

As is apparent from Table 1, the embossing pattern has an effect on thecoefficient of friction of the release liner. A diamond pattern, forexample as illustrated in FIG. 12, may achieve a coefficient of frictionof up to 0.965 or more in a polypropylene release liner—an improvementof nearly 68 percent over the comparative TPO membrane having no releaseliner. Other embossing patterns showing the most significant frictionenhancements include the “taffeta” pattern, for example as illustratedin FIG. 11, and the “matte” pattern illustrated in FIG. 13.

The invention has now been described in detail for the purposes ofclarity and understanding. However, those skilled in the art willappreciate that certain changes and modifications may be practicedwithin the scope of the appended claims.

What is claimed is:
 1. A roofing membrane, comprising: a waterproofinglayer having a top major surface bounded by four edges; and a releaseliner removably attached to and covering or substantially covering thetop major surface of the waterproofing layer, the release liner having acoefficient of friction higher than the coefficient of friction of thematerial of the waterproofing layer.
 2. The roofing membrane of claim 1,wherein the kinetic coefficient of friction of the release liner is atleast 0.6.
 3. The roofing membrane of claim 1, wherein the kineticcoefficient of friction of the release liner is at least 0.7.
 4. Theroofing membrane of claim 1, wherein the kinetic coefficient of frictionof the release liner is at least 0.8.
 5. The roofing membrane of claim1, wherein the kinetic coefficient of friction of the release liner isat least 0.9.
 6. The membrane of claim 1, wherein the waterproofinglayer comprises one or more materials selected from the group consistingof thermoplastic polyolefin (TPO), ethylene propylene diene monomer(EPDM), polyvinyl chloride (PVC), and modified bitumen.
 7. The membraneof claim 1, wherein the release liner includes a chemical additive thatraises the coefficient of friction of the release liner as compared to asimilar release liner lacking the chemical additive.
 8. The membrane ofclaim 7, wherein the chemical additive is a styrene block copolymer. 9.The membrane of claim 1, wherein portions of the exposed surface of therelease liner are raised in relation to other portions.
 10. The membraneof claim 9, wherein the raised portions are embossed.
 11. The membraneof claim 9, wherein the raised portions comprise randomly orientedbumps.
 12. The membrane of claim 9, wherein the raised portions formintersecting lines.
 13. The membrane of claim 1, wherein: the releaseliner includes a chemical additive that raises the coefficient offriction of the release liner as compared to a similar release linerlacking the chemical additive; and portions of the exposed surface ofthe release liner are raised in relation to other portions.
 14. Themembrane of claim 1, wherein the release liner covers the top majorsurface of the waterproofing layer.
 15. The membrane of claim 1, whereinthe release liner substantially covers the top major surface of thewaterproofing layer, leaving uncovered a strip of the top major surfaceof the waterproofing layer at one edge of the top major surface.
 16. Themembrane of claim 1, wherein the release liner is removably attached tothe waterproofing layer without the use of an adhesive.
 17. The membraneof claim 16, wherein the release liner is attached to the waterproofinglayer using heat and pressure.
 18. The membrane of claim 16, wherein therelease liner includes a tackifier.
 19. The membrane of claim 1, whereinthe release liner is removably attached to the waterproofing layer usingan adhesive.
 20. The membrane of claim 1, wherein the release liner isremovably attached to the waterproofing layer using static cling.
 21. Amethod of applying a roofing membrane on a roof, the method comprising:laying a first row of roofing membrane on the roof, the first row ofroofing membrane including a first waterproofing layer and a firstrelease liner on top of a top major surface of the first waterproofinglayer, the first release liner having a coefficient of friction higherthan that of the material of the first waterproofing layer; and laying asecond row of roofing membrane on the roof, the second row of roofingmembrane having a second waterproofing layer and a second release liner,the second release liner having a coefficient of friction higher thanthat of the material of the second waterproofing layer, the second rowof roofing membrane overlapping the first row such that a bottom majorsurface of the second waterproofing layer contacts an uncovered strip atone edge of the top major surface of the first waterproofing layer; andbonding the first and second rows of roofing membrane together in theirarea of overlap.
 22. The method of claim 21, further comprisinguncovering the strip of the top major surface of the first waterproofinglayer by peeling back a portion of the first release liner.
 23. Themethod of claim 22, further comprising removing the portion of the firstrelease liner by tearing the first release liner along a perforation.24. The method of claim 21, wherein the release liner of the first rowof roofing membrane substantially covers the top major surface of thefirst waterproofing layer, leaving uncovered the strip of the top majorsurface of the first waterproofing layer.
 25. The method of claim 21,further comprising removing the first and second release liners.
 26. Amethod of making a roofing membrane, the method comprising: providing apolymeric waterproofing layer having a top major surface; and removablyattaching a release liner to the top major surface of the waterproofinglayer, the release liner having a coefficient of friction higher thanthat of the material of the waterproofing layer.
 27. The method of claim26, wherein removably attaching the release liner to the waterproofinglayer comprises placing an adhesive between the waterproofing layer andthe release liner.
 28. The method of claim 26, further comprisingembossing the release liner.